心电信号时频特性的对比研究

Comparative Study on the Characteristics of Electrocardiac Signals in Time Domain and Frequency Domain

对心电信号的分析存在着时域频域两种方法 ,我对此作了对照研究。用频域滤波的方法 ,分别滤去一定低频成分 ,再 IFFT恢复时域波形 ,时域信号出现了双相 T波。滤去一定高频成分 ,再 IFFT恢复时域波形 ,经适当放大 ,可明显看出高频心电的时域表象 :P波、T波的高频时域表象没有明显结构 ,而 QRS波有明显的结构。 QRS波时限与高频成分有关 ,滤去一定的高频成分 QRS时限延长。QRS波顿挫是高频成分增多所致。心室去极化 QRS复合波有三角脉冲样波形 ,也有非三角脉冲样波形 ,其功率谱具有单峰和指数下降 (倒幂 )特征两种类型。整个心动周期信号、P波、T波的高频谱无明显的规律性 ,而 QRS波有一定的结构。

There are two methods (time domain and frequency domain) for the analysis of electrocardiac signals. In this paper is reported a study on them by way of comparison. With the use of filtering method in frequency domain, certain low frequency components were filtered, the time domain waveform was retrieved by IFFT, and the biphase T wave appeared in time domain. After some high frequency components were filtered, time domain wave was retrieved by IFFT, and amplified, the time domain representation of high frequency ECS could be shown obviously, i.e. there was no evident structure in time domain representation of high frequency components in P- and T-waves, but there was evident structure in high frequency components in QRS complex. The duration of QRS depended upon high frequency components, and it was prolonged by filtering certain high frequency components. The slurring of QRS complex was caused by increasing high frequency components, on ventricular depolarized QRS-complex, there were both triangular pulse-like and a triangular pulse-like waveforms, and their power spectrum had both types of feature, single peak and inversepower spectrum. There was no regularity in the spectrum of entire cycle, P- and T-waves, but these was some structure in QRS wave.